Fuel control mechanism



Nov. 5, 1946;.'

M. E. CHANDLER FUEL CONTROL MECHANISM Filed` July 22 1942 lsbl.

vENToR nEChadler w o, 1 M mw NMF vm@ SS All ,w N 5 9 w QN Patented Nov.5, 11946 41amV FUEL CONTROL MECHANISM Milton E. Chandler, New Britain,Conn., assignolj to Chandler-Evans Corporation, a corporation ofDelaware Application July 22, 1942, Serial No. 451,874

nal combustion engines. A further object of my 'invention is to providesuch an improved controlling mechanism especially adapted to use inconnectlon with airplane engines,v either of the gasoline or fuel-oiloperated type. A still further object of my invention is to provide suchimproved controlling mechanism of the typewherein the fuel supplythrough the injectors to the engine cylinders varies as a function ofair flow to the engine, and wherein improved cooperating mechanism isprovided to control the operation of the fuel injector pump in suchmanner as to maintain the quantity of fuel supplied by the injectors afunction of air flow under all operating conditions of the engineincluding enrichment under overload conditions. A still further objectof my invention is to provide improved controlling mechanism for theinjector pump, wherein this controlling mechanism is controlled byvariations in air flow, and -wherein the operation of said pump is alsosuitably modified by variations in the speed of the engine, while alsoincluding improved cooperating controlling means operative during theidling range. These and other objects and advantages will, however,hereinafter more fully appear.

In the accompanying drawing, I have shown 14 Claims. (C11. 12S-140)engine. In this construction, a connection i leads from the throat ofthe venturi 'I to a control valve casing il enclosing a diaphragm,generally indicated at D. which separates the casing into two expansiblechambers I2 and lil. This connection i0 communicates with the chamber i2below the diaphragm D, while a connection It leads from the scoop 8through a chamber i5 communicating with the chamber i3 through ananeroid operated valve I5. Further, as shown, the diaphragm D comprisesa central portion D' and a peripheral portion i32 surrounding theportion D and having its own periphery clamped between the peripheralportions of component casing members cooperating to form the lcasing il.

. Moreover, note that the portion D' of this diafor purposes-ofillustration one embodiment which my inventio'n may assume in practice.

In this drawing: Y

Figure 1 is a diagrammatic view of my improved mechanism, and

Fig. 2 isa detail view showing the diaphragm valve of Figure 1 in adifferent position thereof.

In this illustrative construction, l'. have illustrated my invention asAapplied to an engine I including a cylinder la and having a suitableservice shaft 2' and injector pump mechanism, generally indicated at 3,driven from the shaft 2 by a wobble cam t and supplying fuel to aninjector E, only one cylinder being shown in order to simplifyillustration.

My improved controllingl mechanism, which controlsv the operation of theinjector pump 3, herein includes controlling mechanism responsive tovariations in air ow to the engine l. As shown, this mechanism includesan air meter d including a usual air venturi l, hereinof the rectangulartype, and having a scoop and suitable throttle means s betweentheventuri i er.: the

dfi

phragm carries usual axially disposed cooperating discs Il and -a ringi8 of larger diameter than I these Vdiscs and has a coiled spring I9biasing the ring i8 and the enclosed central portion D' of the diaphragminto the raised position shown in Figure 1, wherein the ring i8 ispressedagainst an annular series of stops 2li depending from the uppermember 0f the casing il. The stops 2d are spaced so that the samepressure acts on the entire upper surfaceof diaphragm D. As shown,

a coiled spring 2|, lighter than the spring I8,-

acts on. saidupper member as an abutment and is also disposed centrallywith and acts upon the upper face of the discs l1. On the opposite facef the discsil from the spring 2i is a depending button 22 attached tothe adjacent face of a suitable small diaphragm 23 which is suitablyattached to the lower casing member around the edge of an annularchamber 2t. This diaphragm 23 and valve member 22 are normally slightlyraised by fluid pressure in chamber 2t, to provide communication beneaththe diaphragm 23 between this annular chamber 2d and an axial dischargeor drain passage 2b, and the button 22 rises and falls as necessary .tocontrol the escape of iluid from chamber 2t, as hereinafter described.Note here also that connection between the chambers i2 and i3 onopposite sides of the diaphragm D is established by passages 2t and 2lhaving communication between the same controlled by a suitable valvel 28forming a part of a usual manual rich mechanism, `not shown. The totalair pressure differential between the scoop t and the throat of theventuri 'l is a measure of the velocity ofthe flowing/air. This pressurediierential produces a flow of air thru a secondary air passage whichmay be traced from scoop t thru connection it, chamber it, past valve itinto chamber i3, connection 21, pastvnve 2|, mecum-es, chamber n ad econnection .Ilto the throat of venturi 1.

Inthis secondary-air passage, the total pres- Bure dinerentialbetweenthe scoop 8 and the throat oi' venturi A'I may be considered as beingdivided into two' component pressure drops, one y acrossthealtitude'compensating valve `|6 and the other across the restrictioncontrolled 'by valve 23. The pressure responsive valve il cor' rects thepressure dinerential acting on the dia- Phrasm D so that it is anaccurate measure of at its lower end at 39, and also pivotally conanected between lts ends at 40 to a longitudinally A the mass'of airflowing per unit time. rather than Y the velocity of air flow. vUpon'adecrease in air density, such as accompanies an increase in altitude ofan aircraft, the valve I6 moves .toward closed position.- therebyincreasing the proportion of the total fuel pressure differential which,

takesplace scrum valve Ii, and decreasing the` proportion of the totalfuel pressure differential which is effective on\ the diaphragm D, The

' pressure dierential on diaphragm Disthereby correctedfor the decreasein the` mass of air owingper unit time due to the decrease in density. lThe valve 23 is normally in a position where a small fixed restrictionconnects the chambers l2 and I3. It may be manually moved from .thisposition to one -wheretheresriction is substantially closed.` When therestriction. is closed. there is no air now thru the secondary passagejust traced, and hence no pressure drop thru the adjustable rod 4Icontrolling the positionof adjustment cfa valve member 42 in theinjector pump 3.- In the illustrative constructiomthis valve member 42is reciprocable in a fuel inlet chamber 43 in the injector pump casingand 'reciprocably mounted on the front ends of spring pressed plungers.operated by the wobble cam e, a' coiled spring I5 normally biasing' saidvalve member to the left. Herein, this valve member cooperates in its.diiierent longitudinal positions to vary the closing time ofT-shapedinlet pas.. sageways 46 in the plungers 44 in such manner as tovary the amount of fuel supplied to these plungers from a usual fuelpump Il to fuel inlet valve I8. Valve Il then hasno controlling effect,

and the diaphragm D is then subjected v A to the total air pressuredifferential.

The pressure differential on the diaphragmy` D acts in a downwarddirection on the but- Aton' 22, and thereby tends to close the outletpassage 25. 'The pressure dierential on diaphragm 23 acts upwardlyagainst the button 22; and thereby tends to open 'the outlet passage 25.Since the pressure in chamber I2 is small, being customarily measured ininches of water, while the pressure in chamber 2l :is relatively large,being customarily measured in inches of mercury or pounds per squareinch, it may be considered that the force acting thru diaphragm 23 onbutton 22 in a valve opening direction is determined by the pressure inchamber 24, dis-- regarding the effect of variations in pressure inchamber l2.` The pressure diilerential acting downwardly on diaphragm D.as previously described,.is a measure of the mass of air entering theengine. yThe spring 2i assists this air pres- 41a and chamber 431.-Qheck valves I8 and relief .ports 49 communicating with relief passages5@ being also provided.

. As a result of the control of the adjustment of the position of thepiston 36 in accordance with variations in the air now to the engine.and the adjustment of the valve 42 by the piston 36,"lt will be apparentthat the quantity of fuel supplied from the inlet Ila to each infector 5will vary as a function of air now. Further, it willbe noted that whenthe air now increases sufllciently to overcome the spring i9 andincrease the eective area of the diaphragm D, the pressure inpipe 33will then be additionally built Iup in suchmanalso provided. A ballEOYernor; 5I, carried on a suitable engine service shaft, which may'ffbethe sure diierential' but, 'since this is a Arelatively light spring,its ei'l'ect lsnegligible except at very low air flows. The purpose andeect'of spring v2 I'at such low airfiows is explained below.

The position of button. 22 controls the pressure of nuid supplied to afluid motor 35 which controls the displacement of the injector pumpmechwhose outlet pressure is controlled by convenner as thereby toadditionally actuate the" piston i8, i. e. even further, and therebyenrich the mixture as required under. such conditions'ffwhilemaintaining the total j el flows. functionofair now. v, n j Cooperatingwith the mechanism above described and operating to'enablethe abovecontrol to be iniiuenced by variations in enginegspeed, improvedcooperating controlling mechanism is shaft 2 or a suitableshaftfdriventherefrom, is connected to a dependlng'-linltb2 pivoted at 53 andconnected through ac'rosslink 54 near its upper end to the lower endlot-the link-38.v .As a result of thisconnection',` hileythejjrod 4iwill be operated by the piston .3l heretofore described to adjust thevalve 42. theadlustment'of the latter will obviously be modified-by.the. action of the ball governor on the 5 2', the vgovernor moving thelower pivot 39 of the in sch mananism 3. The iiuid is supplied by' agear pump 29,

tional relief valve 30. The fluid may be the-lubrieating oil of theengine, and the pump may be the usual oil pump. Most of the oildischarged by pump 29 passes thru a conduit 32, but a portion of the oilpasses thru a restriction 3l intoal `conduit 33 and-thence thru chamber:fand the outlet controlled by the position o! button 22 into a drain25, which .may be connected to a suitable reservoir or'to the inlet ofpump 29. The fluid motor 35 includes a cylinder in which a piston 3Bismovable.` The nuid under pressure is supplied to the cylinder lfrom aconduit 34 coni nected to conduit 33. The pressure in conduit 33 (iiiA Iner 'as thereby to enable the speed of theengine to modify the effectofgthelaircontrol and accordingly enable the mechanism to operatesatisfactorlly under widely varying conditions.

Under idling conditions. the vquantity of air flowing thru the venturi Iis quite small relative to the dimensions of the venturi. At such times,it hasbeen found that the pressure diiferential between the chambers l2and I3 is not an accu- ,rate measure of the quantity'of air flowing thruthe venturi. I have therefore provided the spring 2| whichactsdownwardly onthe central portion Dv of the ldiaphragm D. At normalair flows, the force oi' spring 2| is so small as compared to the forcedue to the pressure differential acting on .the diaphragm that itsenectis negligible. At low air ilows, however. the effect-of spring 2|on the diaphragm is large as compared to the eiect of Cooperating withthe above described controlling mechanism is also further cooperatingcontrolling mechanism modifying the operation of the injector pumpduring the idlingv range. As

shown, this mechanism includes a cam 55 carried on the throttle shaft 56and cooperating with an adjustable member 51 carried on the lower end ofthe depending link `52. As shown, the latter link is biased toward thecam by a spring 58 and also carries an adjustable stop 59 engageablewith a portion 59a on the engine and which cooperates with the member lin determining the limits of movement of the link 52 by the cam 55;Thus, when the throttle shaft 53 is adjusted into idling position, theabove control mechanism automatically decreases the fuel delivered bythe injector pump 3 to the quantity desired to operation.

It may be stated that the function of spring 2| is to transfercontrolfof the fuel injector mechanism from the diaphragm D to thethrottle during conditions of low air ow. Such conditions occur onlywhen the throttle is within a range of positions adjacent its closedposition, usually termed the idling range. The cam 55 is so de signedthat it is effective to control the injector mechanism only when thethrottle is Within this range of positions. Under such conditions, thespring 2l is eective-to maintain a substantially constant pressure inconduit 33, so that the position of piston 26 is substantially constantand the effective control of the fuel supply is 'provided by thethrottle operated cam 55.

In the operation of the complete mechanism, in normal operation thecentral portion D of the diaphragm D will so control the valve member 22and diaphragm 23 as to maintain the pressure in the pipe 33 a functionof air flow. Consequently, the piston 36 through its connected linkagewill so adjust the valve 42 automatically as to maintain the fuel flowfrom the fuel inlet 41a to the several plungers M also a function of airflow. Further, it will be apparent that as the engine speed varies, theball governor 5I will modify the above control as necessary toautomatically compensate for variations in engine speed, while, dur'-ing idling, the manual adjustment of the throttle shaft 56 will effectthe desired manual adjustment during operation in the idling range. Asthe air flow to the engine increases, however, the normally functioningportion D' of the diaphragm D will be automatically increased in area bythe addition of the peripheral portion D2 thereto, as above described,in such manner as further substantially to build up the pressure in thepipe 33,

and injectorsis provided, with each injector and cylinder successivelysupplied with a suitable charge of fuel through the action of the wobblecam ,4. Further, it will be understood that while I contemplate the useof my improved mechanism effect idling l scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a fuel control mechanism for internal combustion engines, an airconduit, control means responsive to variations in the quantity of airflowing through said conduit,= hydraulic control mechanism controlled bysaid controlling means. fuel injector mechanism including an injectorpump having a valve opened and closed during each cycle of operation ofsaid pump, means con-l trolled by said hydraulic control mechanism forvarying the time of closure of said valve to vary the delivery of saidpump as a function of air flow, and means controlled by the enginethrottle for modifying the closing time of said valve. i

2. In a fuel control mechanism for internal combustion engines, an airconduit,fcontro1 means responsive to variations in the quantity of air.flowing through said conduit, hydraulic control mechanism controlled bysaid control means, fuel injector mechanism including, an injector pumphaving a valve opened and closed during each cycle of operation of saidpump, means controlled by said hydraulic control mechanism for varyingthetime of closure of said valve to vary the delivery of said pump as afunction of air flow, and

means controlled by engine speed for modifying the closing time of saidvalve.

3. In a fuel control mechanism, an air conduit, control means responsiveto variations in the quantity of air flowing through said conduit,hydraulic controlmechanism including a cylinder and a piston thereinreversely adjusted bysaid controlling means as a, function of air flow,fuel 'injector mechanism including an injector pump having a valveopened and closed during each cycle of operation of. said pump, linkageadjustable by said piston to control the time of closure of said Valveto vary the delivery of said pump as a function of air flow, andthrottle operated means for adjusting said linkage to automatically varythe operation of said valve and the delivery of the pump during idling.

4. In a fuel control mechanism, an air conduit, control means responsiveto variations in the quantity of air flowing through said conduit,hydraulic control mechanism including a cylinder and a piston therein.reversely adjusted by said controlling/ means as a function of air ow,fuel injector mechanism including an injector pump having a valve openedand closed during each cycle of operation of said pump, linkageadjustable by said piston to control the time of closure of said valveto vary the delivery of said pump as a function of air flow, and enginespeed operated means for adjusting said linkage to modify vthe closingtime of said valve in accordance with engine speed.

5. In a fuel supply system for an internal combustion engine, a conduitfor air flowing to said engine 'for combustion purposes, meansassociated with said conduit for producing two unequal presinjectormechanism including a plurality of reciprocating pumps for supplyingfuel directly to the cylinders of said engine,'means for controlling thefuel displacement per stroke of said pumps,

means responsive to the difference of said two unequal air pressuresincluding a flexible diaphragm, means attached to said diaphragm foroperating said fuel displacement controlling means and effective toincrease said displacement in response to an increase of said differenceof air pressures, spring means biasing said diaphragm in a direction toincrease said fuel output, said spring meansl being effective when saiddifference of air pressures is small to operate said diaphragm in adisplacement increasing direction, andfmeans operative as an incident tomovement ofl said throttle means into a range of positions adjacent saidclosed position to reduce the displacement of said pumps regardless ofthe position of said diaphragm.

m i 6 A fuel supply system for a. m t ple cylinder 25 bustin enginecomprising injector pump mech internal combustion engine, comprising aplurality of reciprocating inJector pumps for supplying fuel to thecylinders ofsaid engine, means 'for controlling the fuel displacementper-stroke offsaid pumps, fluid motor means including an expansiblechamber having a. movable wall for operating said capacity controlmeans, valve means for controlling the pressure in said chamber, apassage for air flowing to said engine for, combustion purposes, meansresponsive to the rate oi' flow of air thru said passage forcontrolling-said ,valve means, throttle means for controlling the flowof air thru said passage,

and means eective when said throttle means is in a, predeterminedrangeof positions'to move said displacement control means concurrentlytherewith and independently of said motor means. '7. A fuel .supplysystem for an internal combustion engine, comprising injector pumpmechanism for supplying fuel to said engine, means for controlling thecapacity of said pump mechanism, fluid motor means, a floating lever,means connecting said capacity control means and said motor means tospaced points on said lever, a passage for air flowing to said enginefor combustion purposes, means responsive to the rate of flow of airthru said passage for controlling said motor means, throttle means forcontrolling the now of air thru said passage, and means connecting saidthrottle means to another point on said lever, so that'said capacitycontrol means may be positioned thereby independently of said motormeans.

8. A fuel supply system for an internal combustion engine, comprisinginjector pump mechanism for supplying fuel to said engine, means forcontrolling the capacity of said pump mechanism, fluid motor means, afloating lever, means connecting said capacity control means and saidmotor means to spaced points on said lever, a passage for air flowing tosaid engine for combustion purposes, means responsive to the rate of owof air thru said passage for controlling said motor means, throttlemeans for controlling the flow of air thru said passage, and means operative to connect said throttle means to another point on said leverwhen said throttle means is in a range of positions near its closedposition, so that said capacity control ymeans is then p anism forsupplying fuel to said engine, means for controlling'the capacity ofsaid pump mechanlsm, uid motor means, a floating lever, means connectingsaid capacity control means and said motor means to spaced points onsaid lever, a

passage for air flowing to said engine for combustion purposes, meansresponsive to the rate of flow of air thru said passage for controllingsaid motor means, throttle means for controlling the flow of air thrusaid passage, cam means connected to said throttle means for concurrentmovement therewith, and follower means for'said cam means fortransmitting motion to another point on said lever, said cam andfollower means being effective to move said` lever when said throttlemeans is in a range of positions adjacent itsclosed position, so thatsaid capacity, control independently of said motor means.

l0. A fuel supply system for an internal commeans is then positioned bysaid throttlev meansl anism for supplying fuel to said engine, means forcontrolling the capacity of said pump mechanism, fluid motor means, afloating lever, means connecting said capacity control means to anintermediate point on said lever, means connect-y ing saidI motor meansto one end of said lever, a passage for air flowing to said engine forcombustion purposes, means responsive to the rate of flow of air thrusaid passage for controlling 35 said motor means, throttle means forcontrolling the Aflow of air thru said passage, a secondlever pivoted atone end and connected by a link to `the other end of said floatinglever, means biasing said, second lever in a direction to increase thecapacity of said pump mechanism, stop means for limiting the movement ofsaid second lever by said biasing means, means responsive to the speedof said engine for moving said second lever against said biasing means,and cam means connected to said throttle means for moving said secondlever against said biasing means when said throttle means is in a rangeof positions adjacent its closed position.

11. A fuel supply system for an internal combustion engine, comprisinginjector' pump mechanism for supplying fuel to said engine, means forcontrolling the capacity of said pump mech'- anism, iluid motor means, afloating lever, means connecting said capacity control means and said5,', motor means to spaced points on said lever, a

passage for air flowing to said engine for combustion purposes, meansresponsive to the rate of ilow of air thru said passage for controllingsaid motor means, 'and means responsive to the 50,/ speed of said enginefor positioning another point on said lever and thereby moving saidcapacity control means independently of the said motor means.

l2. A fuel ,supply system for an-internal com- 35 bustionengine,comprising pump mechanism for supplying fuel to said engine, means forvarying the capacity. of said pump mechanism,l a floating lever, aconnection between said capacity varying means and a central point onsaid lever, iluid motor means for positioning one end of said lever,means responsive to the power output of -said engine for controllingsaid fluid motor means, and means responsive to the speed of said enginefor positioning the opposite end of said lever.v A

i3. A fuel supply system for an internal combustion engine, comprisingpump mechanism for supplying fuel to said engine, means for varying thecapacity of said pump mechanism, s, floating lever, a connection betweensaid capacity -varying means and a central pointcn said leverI iiuidmotor means for positioning onev end of said lever, means responsive tothe power output of` sive to the speed of said engine associated withsaid other end of said lever and effective to position said otherendwhen the speed exceeds a predetermined value regardless of saidmanually operable means.

14. A fuel supply system for an internal combustion engine, comprisingpump mechanism for supplying fuel to said engine, means for ying thecapacity oi said pump mechanism, floating lever means, a connectionbetween said capacity varying means and a central point on said levermeans, uid motor means for positioning one end-of said lever means,means responsive to the power output of said engine for'controlling saiduid motor means, a manually operable element positioned adjacent theother end of said lever means, spring means biasing said other end intoengagement with said element so that said other end is positioned bysaid element, 4means responsive to the speed of said engine andassociated with said other end of said lever means and effective whensaid speed exceeds a predetermined value to move said other end of saidlever means out of engagement with said manually operable element sothat the position oi said other end is thenkdetermined by said speedresmnsive means and said spring means.

